Hyper1

Amp draw is only used as a guide,I look at it after I rebuild a motor and then have a reference for when it is dropping off and needs to be rebuilt again.

rcnewb2004

I agree with sosidge, but my newbness makes me ask, can a motor perform well on a track if it has unreasonable ampdraw numbers on the charger? Afterall, if a motor cannot even perform well with no load, how can it perfom well under stress?

also I am wondering for the original element 19T motor, what are some "good" (healthy) ampdraw numbers under no load at 2v?


And do large amp draw numbers mean a "better" motor or a "worse" motor... ?

I was thinking... if the motor had a load on it... the amp draw would increase... but then again... if a motor has low resistance, it would also have a large amp draw... this has left me confused... any gurus to help me out?

Skiddins

The problem with the way you are testing (A Motor Checker etc does the same) is that you are not getting any true figures for performance

Larger amp draw means less efficiency, the problem is finding out whether this reduced effiency is is coming out as heat or torque.

I had an Axiom monster that had low revs but monstrous torque and only pulled 4.7A @ 5V

I have also managed to get a similar motor to draw 17A @5V, this had a lot more revs but less torque, and 30 secs after running it flat out off load the air coming out would burn my hands (I was too scared to actually put it under load in my car )

Faster wind motors have lower resistance, that's why they're faster, the stock class motors are all virtually identical in resistance (by design) which is why we waste too much money experimenting with bruhses and springs etc.

If the motor has high current draw but doesn't heat up as quickly as another motor with the similar draw, take the motor that runs cooler and use the max revs as a guide to gearing it

Remember, rev's off load mean nothing if it doesn't have to torque to use them.

Skiddins

OldNSlow2

iTrader: (1)

After years of using my CE dyno and checking amp draw I can tell you this much:

High amp draw with the same design motor will run more RPM, I am talking stock motors here.

On the dyno high amp draw will always run more RPM but not always make more power. The result on the track is you need a lower gear ratio (smaller pinion).

Low amp draw below a certain amount is not very good, I have found 5 to 6 to be the lowest amp draw to make much power. However different design motors pull different amounts of amp draw. For instance, I have never had a CO27 draw below 6 amps that is worth putting in the car.

After years of playing with a dyno I have pretty much given up and use amp draw as my tool to see if the motor is any good. My fastest CO27's pull 8 to 11 amps.

In 12th scale when batteries were an issue as far as run time we would cut the brushes down on both sides get very low amp draw (like 4) and gear it to the moon. Now it is big amp draw and low gearing because the battery can make 8 minutes. So it depends on your situation before anyone can really give you a good answer.

rcnewb2004

So trying to put my head to this I have got:

Large amp draw means the motor is consuming more power.
Whether the power is used to produce torque or heat cannot be determined by simply using amp draw.

A motor with more torque generally produces lower ampdraw figures when tested off load.

A motor with more rpm generally produces higher ampdraw figures when tested off load.

A good method to use ampdraw figures, is to compare motors that have the same ampdraw figures and look at their temperature curves.

The motor that runs cooler while drawing the same number of amps would most likely be using its power more efficiently (converting it into torque rather than heat). Therefore the cooler motor is a better choice, and can be geared higher to produce more rpm.

Correct me if I am wrong.

I did goto school, so I think I can understand this stuff if someone is willing to take some time to write stuff!

morris

iTrader: (44)

i agree with alot of what people are saying on here....exspecially the whole how the motor will feel on the track...

like higher amp draw will drain more battery...so basically you would have to keep tabs on how much battery is left after the race and so forth...

alot of my motors after being cleaned cut and lubed will run about 7-8 amps.
i for the most of it could always keep up...

alot of guys do runa fan when running a motor to put a little bit of a load on it.....when really the car is pushing out what....?7.2 volts.....try running like that once....shuts my thirty's off all the time.....

but to be as honest as i can be....run what ya got and have fun with it.

rcnewb2004

7-8 amp draws?? wow.... offload? what motors are u guys running and at what voltage?

morris

iTrader: (44)

co27 or a monster stock..
using a break in fan....run at 2 volts...

Jake S

iTrader: (67)

Monster1 8.91 (P+ P- 767+ 766-)
Monster2 7.97 (P+ P- F+ F-)
Monster3 7.33 (P+ P- F+ F-)
Monster4 6.87 (P+ G- F+ E-)

CO271 6.84 Amps (P+ P- F+ F-)
CO272 6.34 Amps (P+ P- 767+ 766-)

Trinity has an R Brush that i saw in a recent xtreme rc mag, i want to try that with P+ P-, its suppose to be the same compound as the 767s brushes from reedy.

Ultra1 7.83 (P+ P- XXX+ 4383-)
Ultra2 7.75 (P+ G- XXX+ XXX-)
Ultra3 6.85 (P+ P- 4383+ 4383-)

all my numbers after all cleaned and relubed, without a fan or pinion on....

Johnny Carey

iTrader: (10)

Purples are too heavy for RnD. You should be running reds on both sides. Reds will give you more torque.

morris

iTrader: (44)

well said and bluntly..................lol

either way you look at it reds on both sides is the best way to go for stock motors....

purples better for 19 turn...

Big B

iTrader: (4)

Don't get caught up in what the #'s, as said before a couple times "the Best Dyno is the Track"

Jake S

iTrader: (67)

definately not planning on it, but with "new" motors, its a good way to find your "testing" order...hah

MR JOLLY

it does if you know what your doing
But it does mean nothing if you don`t want to work for it & you want the gearing solution handed to you on a plate

it doesn`t translate from one type to another ie;roar-monster
but if you run 1 type of 27t then every motor is good
like skiddens says he has a 4.7a monster does not mean it`s bad ,it just needs different gearing to your 8a monster that`s all

i regurlay see 8+ amps @2v
if i see a high amp draw one ,then i would gear it @7.8 & a 6a @7.1 at said track

there is a way to gear different amp draw motors in a way that you be in the ball park on the first run

best dyno ;TRACK
best setup;;EXPERIENCE,KNOWLEDGE
best motor;;PROPERLY GEARED ONE

MR JOLLY

POT LUCK
you can buy 3 co27t or 3 monsters or 3 roars & they all be different

once you find a 8+ 27t look after it for race days ,use the 6-7a motors for clubs

i know some tuners won`t run 8+ amp motors as they get to hot at the end of run & tail off on the pace ,they preferr 7-8a motor's & have consistency through the race

just like battery lables ,Don`t get hooked/fooled on numbers
higher doesnot mean better
lower does not mean bad